The present invention relates to a wireless optical pointing device.
A mouse is a commonly used input device. A wheel mouse processes displacement, button, and interface signals and communicates with a computer via an interface using the mechanical structure of its wheel and a micro-controller chip. An optical mouse replaces the mechanical structure of the wheel mouse with a complementary metal oxide semiconductor (CMOS) photo sensor chip capable of optical navigation. The CMOS photo sensor detects a series of continuous images on an operating surface. The displacement of the optical mouse can be determined by processing the images. Moreover, the mouse can communicate with the computer wirelessly via signal transmission.
FIG. 1a is a diagram of a conventional wireless optical mouse 10. FIG. 1b is a diagram showing a photo sensor 13, an MCU (Micro-Controller Unit) 14, a RF (Radio Frequency) transmitter 15, and two crystal oscillators 16 and 17 inside the wireless optical mouse 10 in FIG. 1a. As shown in FIG. 1b, typically, a wireless optical mouse 10 has a photo sensor 13, an MCU (Micro-Controller Unit) 14, and a RF transmitter 15. The photo sensor 13 is provided with an oscillation frequency by a crystal oscillator 16. The RF transmitter 15 is provided with an oscillation frequency by another crystal oscillator 17. When the wireless optical mouse 10 is operated, the photo sensor 13 outputs a displacement of the wireless optical mouse 10 to the MCU 14. The MCU 14 then converts the received displacement of the wireless optical mouse 10 and button state information as a modulation signal and outputs the modulation signal to the RF transmitter 15. Thus, the RF transmitter 15 transmits the displacement and the button state information to a computer (not shown in drawings) via a RF carrier wave (not shown in drawings). The RF carrier wave is provided by the crystal oscillator 17.
Due to frequency band limitations, the RF transmitter 15 of the wireless optical mouse 10 typically operates within a frequency in the citizen band (CB) such as 27 megahertz (MHz). Thus, the crystal oscillator 17 provides a RF carrier wave of 27 MHz to the RF transmitter 15. Additionally, the photo sensor 13 typically operates at 18.43 MHz, so the crystal oscillator 16 provides an oscillation signal of 18.43 MHz to the photo sensor 13. Thus, the wireless optical mouse 10 requires two separate crystal oscillators 16 and 17, thus increasing production cost and power consumption.